During Binocular Accommodation Facility testing, convergence insufficiency patients may be unable to clear which type of lenses?

• A. Plus lenses
• B. Minus lenses
• C. Lenses with varying power
• D. No effect

Answer: (A)

Accommodation facility tests how quickly the eyes can shift focus when lenses that demand more or less accommodation are flipped in front of the eyes. In convergence insufficiency, the vergence system isn’t robust enough to maintain single, clear vision through rapid changes in focus. When plus lenses are viewed, the eye’s accommodation demand drops, which changes the vergence effort the brain must make to keep the image fused. For many CI patients, this rapid adjustment in vergence while accommodation is being relaxed is challenging, making it harder to sustain fusion and therefore harder to clear the plus lens quickly. The result is a tendency to struggle with the plus-flipper condition during testing. Lenses with varying power and the no-effect option aren’t specific lens challenges in this context, and minus lenses impose a different accommodative/vergence demand that CI patients may respond to differently.